1. Field of the Invention
The present invention relates generally to circuits for regulating charging of storage batteries by photovoltaic arrays, and more particularly to a circuit that prevents overcharging of the storage battery.
2. Description of the Related Art
U.S. Pat. No. 4,453,119, issued to Staler et al., shows an electrical charging control apparatus for regulating the charging of a rechargeable battery by a solar panel. Control of the charging is through a relay which directly connects the solar panel to the terminals of the battery. The relay is opened and closed by signal testing circuitry which opens the relay when the voltage at the battery reaches a chosen charging threshold. The voltage level of the battery is tested against a reference voltage.
U.S. Pat. No. 4,306,183, issued to Wright, shows a voltage regulations circuit including an operational amplifier connected as an integrator which generates an output signal representing the time integral of the error between the voltage across the battery and a reference voltage provided by a zener diode. The integrator circuit output is connected to a series of voltage comparators, each of which controls one of a series of transistor shunt switches, wherein a plurality of solar arrays are sequentially disconnected from the battery as the voltage of the battery increases during charging. The solar arrays are disconnected from the battery by having their outputs shunted to ground by transistor switches 21-25, thereby causing diodes connected between the solar arrays and the battery to become reverse biased.
The above described related art is believed to be unnecessarily complex for the purpose of regulating the charging of a storage battery by a photovoltaic array. It would be desirable to provide a circuit for regulating charging of a storage battery by a photovoltaic array that is simple, efficient and inexpensive. This and other desires are satisfied by the present invention.